315 for 4 reps is an impressive amount of weight. I would keep squatting that weight and try to get 5 reps, then 6 reps, then 7, then 8.
Once you can get 315 for 8, you should be able to do 325 for 4. I would then do the same thing with 325. Try to get 325 for 5, then 6, 7, 8.
Keep doing that and eventually you will be able to squat 405 for 4!
I am a big advocate of training everything twice per week when on cycle. The more often you train a muscle, you more growth stimulus you get. You won't be able to use quite the amount of volume as you would normally but scientifically, it's the fastest way to grow. I like to first train the muscle in the heavy/powerlifting sense each week and then train the muscle in a pump/bodybuilding style later in the week.
This is my current training split:
Day 1:
Leg strength
Day 2:
Push strength + abs
Day 3:
Pull strength
Day 4:
Leg hypertrophy
Day 5:
Push hypertrophy + abs
Day 6:
Pull hypertrophy
Day 7:
20 minutes intervals, 20 minutes steady state cardio. Abs
Give it a try if it interest you.